Index: cfe/trunk/include/clang/Driver/Driver.h
===================================================================
--- cfe/trunk/include/clang/Driver/Driver.h
+++ cfe/trunk/include/clang/Driver/Driver.h
@@ -277,6 +277,12 @@
                               SmallString<128> &CrashDiagDir);
 
 public:
+
+  /// Takes the path to a binary that's either in bin/ or lib/ and returns
+  /// the path to clang's resource directory.
+  static std::string GetResourcesPath(StringRef BinaryPath,
+                                      StringRef CustomResourceDir = "");
+
   Driver(StringRef ClangExecutable, StringRef TargetTriple,
          DiagnosticsEngine &Diags,
          IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS = nullptr);
Index: cfe/trunk/lib/Driver/Driver.cpp
===================================================================
--- cfe/trunk/lib/Driver/Driver.cpp
+++ cfe/trunk/lib/Driver/Driver.cpp
@@ -89,6 +89,33 @@
 using namespace clang;
 using namespace llvm::opt;
 
+// static
+std::string Driver::GetResourcesPath(StringRef BinaryPath,
+                                     StringRef CustomResourceDir) {
+  // Since the resource directory is embedded in the module hash, it's important
+  // that all places that need it call this function, so that they get the
+  // exact same string ("a/../b/" and "b/" get different hashes, for example).
+
+  // Dir is bin/ or lib/, depending on where BinaryPath is.
+  std::string Dir = llvm::sys::path::parent_path(BinaryPath);
+
+  SmallString<128> P(Dir);
+  if (CustomResourceDir != "") {
+    llvm::sys::path::append(P, CustomResourceDir);
+  } else {
+    // On Windows, libclang.dll is in bin/.
+    // On non-Windows, libclang.so/.dylib is in lib/.
+    // With a static-library build of libclang, LibClangPath will contain the
+    // path of the embedding binary, which for LLVM binaries will be in bin/.
+    // ../lib gets us to lib/ in both cases.
+    P = llvm::sys::path::parent_path(Dir);
+    llvm::sys::path::append(P, Twine("lib") + CLANG_LIBDIR_SUFFIX, "clang",
+                            CLANG_VERSION_STRING);
+  }
+
+  return P.str();
+}
+
 Driver::Driver(StringRef ClangExecutable, StringRef TargetTriple,
                DiagnosticsEngine &Diags,
                IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS)
@@ -119,17 +146,7 @@
 #endif
 
   // Compute the path to the resource directory.
-  StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
-  SmallString<128> P(Dir);
-  if (ClangResourceDir != "") {
-    llvm::sys::path::append(P, ClangResourceDir);
-  } else {
-    StringRef ClangLibdirSuffix(CLANG_LIBDIR_SUFFIX);
-    P = llvm::sys::path::parent_path(Dir);
-    llvm::sys::path::append(P, Twine("lib") + ClangLibdirSuffix, "clang",
-                            CLANG_VERSION_STRING);
-  }
-  ResourceDir = P.str();
+  ResourceDir = GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 void Driver::ParseDriverMode(StringRef ProgramName,
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -26,6 +26,7 @@
 #include "clang/Basic/Visibility.h"
 #include "clang/Basic/XRayInstr.h"
 #include "clang/Config/config.h"
+#include "clang/Driver/Driver.h"
 #include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Options.h"
 #include "clang/Frontend/CommandLineSourceLoc.h"
@@ -1893,18 +1894,7 @@
                                                  void *MainAddr) {
   std::string ClangExecutable =
       llvm::sys::fs::getMainExecutable(Argv0, MainAddr);
-  StringRef Dir = llvm::sys::path::parent_path(ClangExecutable);
-
-  // Compute the path to the resource directory.
-  StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
-  SmallString<128> P(Dir);
-  if (ClangResourceDir != "")
-    llvm::sys::path::append(P, ClangResourceDir);
-  else
-    llvm::sys::path::append(P, "..", Twine("lib") + CLANG_LIBDIR_SUFFIX,
-                            "clang", CLANG_VERSION_STRING);
-
-  return P.str();
+  return Driver::GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
 static void ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
Index: cfe/trunk/test/Index/pch-from-libclang.c
===================================================================
--- cfe/trunk/test/Index/pch-from-libclang.c
+++ cfe/trunk/test/Index/pch-from-libclang.c
@@ -1,7 +1,11 @@
 // Check that clang can use a PCH created from libclang.
 
-// FIXME: Non-darwin bots fail. Would need investigation using -module-file-info to see what is the difference in modules generated from libclang vs the compiler invocation, in those systems.
-// REQUIRES: system-darwin
+// This test doesn't use -fdisable-module-hash and hence requires that
+// CompilerInvocation::getModuleHash() computes exactly the same hash
+// for c-index-test and clang, which in turn requires that the both use
+// exactly the same resource-dir, even without calling realpath() on it:
+// - a/../b/ and b/ are not considered the same
+// - on Windows, c:\ and C:\ (only different in case) are not the same
 
 // RUN: %clang_cc1 -fsyntax-only %s -verify
 // RUN: c-index-test -write-pch %t.h.pch %s -fmodules -fmodules-cache-path=%t.mcp -Xclang -triple -Xclang x86_64-apple-darwin
Index: cfe/trunk/tools/libclang/CIndexer.cpp
===================================================================
--- cfe/trunk/tools/libclang/CIndexer.cpp
+++ cfe/trunk/tools/libclang/CIndexer.cpp
@@ -14,6 +14,7 @@
 #include "CXString.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/Version.h"
+#include "clang/Driver/Driver.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/MD5.h"
@@ -62,7 +63,7 @@
 #endif
 #endif
 
-  LibClangPath += llvm::sys::path::parent_path(path);
+  LibClangPath += path;
 #else
   // This silly cast below avoids a C++ warning.
   Dl_info info;
@@ -70,13 +71,11 @@
     llvm_unreachable("Call to dladdr() failed");
 
   // We now have the CIndex directory, locate clang relative to it.
-  LibClangPath += llvm::sys::path::parent_path(info.dli_fname);
+  LibClangPath += info.dli_fname;
 #endif
 
-  llvm::sys::path::append(LibClangPath, "clang", CLANG_VERSION_STRING);
-
   // Cache our result.
-  ResourcesPath = LibClangPath.str();
+  ResourcesPath = driver::Driver::GetResourcesPath(LibClangPath);
   return ResourcesPath;
 }